Spanish patent 411,713 and Spanish utility model Publication 194,295 related to improvements to packet expeller devices useful in automatic product vending-machines dispensing products located in columns formed inside the machine.
In both Spanish patent 411,713 and Spanish utility model Publication 194,295 the expeller device comprises a horizontal platform forming a base supporting the column of packets to be dispensed. This platform is mounted to rotate and is associated with mechanical elements so that rotation is able to take place and the bottom packet can to leave. The rest of the packets are held by an extension of the platform, working with similar mechanical elements linked to the whole system.
In these two documents, the mechanism is rather complex due to the number of parts needed for the operation altogether involving expelling the bottom packet, holding the rest, guiding and driving such packet towards the outlet and so forth to be carried out.
Spanish patent 8703213 affords provides a simpler solution, using a box to pile the packets. A rotating base is mounted upon a shaft to which an arm is respectively articulated to rotate with such base in such a way that when the latter swings down, it allows the bottom packet in the column to drop sliding. The arm rotates at the same time in order for its end to drive and press against a side of the penultimate packet, holding the entire column. The two elements (rotating base and arm) are returned to their original positions by respective springs, that must be suitably scaled in order to perform effectively. Furthermore, the springs, when used, undergo the usual deformation and stretching that leads to a faulty operation of the mechanism.
Spanish patent 8801706 provides a solution that is also simple, using a sort of grip that holds the penultimate packet in the column and hence logically the whole column. The bottom packet is expelled when the base supporting the entire column of packets rotates. The mechanism is hinged to the end of the shaft of an electric magnet. So that when the magnet coil is energised its respective core moves axially to either close the grip holding the entire column of packets from the next to last one, causing the supporting platform to swing at the same time to expel the bottom packet, or the base to swing in the opposite direction so that, when the bottom packet has been expelled, the remaining packets in the column shall rest upon the platform. In this operation, the grip is simultaneously opened in order for the column of packets to precisely move down and rest upon the bottom supporting base or platform.
Although this solution can be simple in its overall construction, it has a severe drawback in that its operation is dependent upon the operation of an electric magnet, which implies the need for a high circuit intensity and a violent activation. Moreover, high precision is required to assemble and link the parts, which without doubt renders the mechanism more expensive because the whole manufacturing and assembling process must be carried out with precision and within minimum tolerances for the system to work properly.
Another drawback in classic systems lies in that the system holding the column of packets gradually strains the product in proportion to the stroke of the holding mechanism.
Another solution is set out in Spanish patent 8900887 for a unit product extractor. The pile of packets in the extractor lies upon a rotating platform. The pile having a grip to fix or lock the second packet and all packets located above the same, at the stage of rotation of the bottom plate or platform. The mechanical solution adopted being in this case is the transmission of movement from a drive unit to a cogwheel, this cogwheel receiving a lever eccentrically that is in turn hinged to the base of the rotating platform. Consequently, depending upon the position of the lever, the platform holding the packets stays horizontal or swings down. The supporting platform itself drives, by means of an L-shaped extension at one of its ends, the grip holding the second packet, opening the same when the platform is horizontal to allow the pile to move down due to gravity.
This solution has a number of drawbacks that are essentially as follows:
There is a direct action between the mechanism holding the column or pile of packets and the mechanism extracting the same. PA1 Locking and holding of the pile of packets subject to the rotation of the bottom platform takes place at the same time as rotation begins. PA1 The last packet drops due to simple gravity, which, on the one hand, entails an absence of a swift step and, on the other, entails a risk that moisture or other problems may cause the packet to stick to the platform. PA1 The mechanism holding the column of packets and the mechanism extracting the same are independent. PA1 The column of packets is held with a constant force without the gradual activation mechanism being involved. PA1 Thrusters are used to expedite extraction. PA1 Front projections are included in the thrusting element developed upwards of the products dispensing column, designed to draw apart bottom packets in the column that may have become stuck.
These drawbacks are fully solved by the mechanism forming the subject matter of Spanish patent 9002052 which is a substantial step forward in this field. The significant characteristics of this mechanism relate to the following aspects:
More specifically, the mechanism of Spanish patent 9002052 provides the use of a micromotor having the appropriate gear, its shaft being fitted with a triple cam, such that while the top cam holds the column of packets, from the last but one, pressing against the same, the bottom cam is linked to a platform supporting the column, allowing the same to-swing as appropriate to allow the packet to be expelled, obviously immediately after the top cam acts to fix the remaining packets. In the meantime, the middle cam works precisely to expel by thrusting, upon turning, the said bottom packet in the column, the packet sliding on the sloped platform.